Michael L. Gran has posted Schmolester, a simple P2P program written in Scheme, based on MoleSter 0.0.2, and distributed under GPL.

It doesn't seem to be a minimal-byte challenge attempt, because it's several kilobytes and uses a lot of long identifiers that could obviously be shortened.  The author is going for readability and simplicity instead.  I haven't tested the code.  He says it's expected to be protocol compatible with MoleSter 0.0.2, which means that it'll probably work with 0.0.4 as well because the basic protocol is unchanged.  There might be a problem with an 0.0.4 peer not closing the last file received when it's on an otherwise-quiet network with a lot of earlier-MoleSter and/or Schmolester peers, because of the byte-saving implicit close technique in 0.0.4.  That could be corrected by the 0.0.4 peer putting an i/ or h/ command on its command line after the last g/ command.  Also note that MoleSter versions prior to 0.0.4, and presumably Schmolester, don't do the implicit peer discovery introduced in 0.0.4, so 0.0.4 peers may have to try harder with i/ and h/ to link into a network with a lot of older-version peers.